As of 16 March 2017, confirmed cases of yellow fever virus infection in humans were reported in Rio de Janeiro State, and epizootics and human cases are under investigation for yellow fever virus infection in São Paulo State. These reports are consistent with the increased yellow fever activity observed in other States (Espírito Santo and Minas Gerais) sharing the same ecosystem - tropical and sub-tropical moist broad leaves forest. As of 16 March 2017, there is no evidence of human cases of yellow fever virus infection transmitted by Aedes aegypti, the vector that could sustain urban transmission of yellow fever.

Therefore, the WHO Secretariat has determined that the State of Rio de Janeiro, with the exception of the urban areas of Rio de Janeiro City and Niterói, and the State of São Paulo, with the exception of the urban areas of São Paulo City and Campinas, should also be considered at risk for yellow fever transmission.

Consequently, vaccination against yellow fever is recommended for international travellers visiting those areas in the States of Rio de Janeiro and São Paulo. The typology of activities that international travellers anticipate to undertake while visiting areas determined to be at risk for yellow fever transmission should be weighted in the risk-benefit analysis informing the individual decision to be immunized against yellow fever.

There are no other additional changes with respect to other areas of Brazil determined to be at risk for yellow fever transmission in 2013, on 31 January 2017, and 6 March 2017.

The determination of new areas considered to be at risk for yellow fever transmission is an ongoing process and updates will be provided regularly.

The current advice by the WHO Secretariat for international travellers going to areas of Brazil deemed to be at risk is the following:

Vaccination against yellow fever at least 10 days prior to the travel. Note that, as per Annex 7 of the International Health Regulations (2005), a single dose of a yellow fever vaccine approved by WHO is sufficient to confer sustained immunity and life-long protection against yellow fever disease. Travellers with contraindications for yellow fever vaccine (children below 9 months, pregnant or breastfeeding women, people with severe hypersensitivity to egg antigens, and severe immunodeficiency) or over 60 years of age should consult their health professional for advice;

Adoption of measures to avoid mosquito bites;

Awareness of symptoms and signs of yellow fever;

Seeking care in case of symptoms and signs of yellow fever, while travelling and upon return from areas at risk for yellow fever transmission.

For 2017, updates on requirements for the International Certificate of Vaccination or Prophylaxis, with proof of vaccination against yellow fever, and WHO vaccination recommendations for international travellers, are available on the WHO International Travel and Health website: Annex 1 and country list. More specific information about requirements for the International Certificate of Vaccination or Prophylaxis, with proof of vaccination against yellow fever, implemented by Member States in the Region of the Americas is available on the PAHO yellow fever website.